Unit V - Content Providers, SQLite Programming and Location Based Services

Content Provider: A core Android component that encapsulates relational data and provides a secure, standardized interface for sharing data across different applications.

Content URI Architecture: Formatted as content://authority/path/id

• content://: Standard scheme identifying it as a Content URI.
• authority: Unique package identifier string (e.g., com.example.provider).
• path: Identifies table or dataset (e.g., /contacts).
• id: Optional specific record ID (e.g., /contacts/5).

ContentResolver Methods: getContentResolver().query(uri, projection, selection, selectionArgs, sortOrder), insert(), update(), delete().

SQLite: A lightweight, serverless, transactional, zero-configuration embedded SQL database engine built into the Android operating system.

SQLiteOpenHelper Abstract Class: Manages database creation and version management:

• onCreate(SQLiteDatabase db): Executed when database is created for the first time. Executes SQL DDL (db.execSQL("CREATE TABLE ...")).
• onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion): Executed when database version number increases. Drops tables or migrates schemas.

SQLiteDatabase CRUD Operations:

• Create (Insert): ContentValues values = new ContentValues(); values.put("name", "John"); db.insert("users", null, values);
• Read (Query): Cursor cursor = db.query("users", projection, "age > ?", new String[]{"18"}, null, null, "name ASC");
• Update: db.update("users", values, "id = ?", new String[]{"1"});
• Delete: db.delete("users", "id = ?", new String[]{"1"});

Cursor Navigation: Iterating query results:

if (cursor != null && cursor.moveToFirst()) {
    do {
        int id = cursor.getInt(cursor.getColumnIndexOrThrow("id"));
        String name = cursor.getString(cursor.getColumnIndexOrThrow("name"));
    } while (cursor.moveToNext());
    cursor.close();
}

Android JSON Parsing:

• JSONObject jsonObject = new JSONObject(jsonString);
• String title = jsonObject.getString("title");
• JSONArray jsonArray = jsonObject.getJSONArray("items");
• Iterate through array indices: JSONObject item = jsonArray.getJSONObject(i);

Location-Based Services (LBS):

• Providers: GPS_PROVIDER (high accuracy, satellite based, outdoors) vs NETWORK_PROVIDER (cellular tower / Wi-Fi triangulation, fast, lower battery).
• FusedLocationProviderClient: Google Play Services unified location API optimizing accuracy and power consumption.
• Permissions: ACCESS_FINE_LOCATION (GPS accurate to meters) and ACCESS_COARSE_LOCATION (city block accuracy).
• Geocoder: Forward Geocoding (Address text $\rightarrow$ Latitude/Longitude) and Reverse Geocoding (Latitude/Longitude $\rightarrow$ Street Address).